The inventor has developed a hydraulic power generating apparatus described in Patent literature 1 generating power by utilizing water flow as being installed to a river, an artificial waterway or the like. Such a hydraulic power generating apparatus starts to be installed to a small river and a first-class river.
Owing to power generation performed by utilizing small hydraulic power such as flow in a river, the hydraulic power generating apparatus has been a nonconventional breakthrough apparatus capable of performing hydraulic power generation effectively at low cost.
However, newly-required improvement points have appeared through actual installation of the hydraulic power generating apparatus. The required improvement points mainly include the following two issues.
One is a problem of maintenance. Since the hydraulic power generating apparatus performs hydraulic power generation as being installed to a waterway having flow, a turbine continues to be rotated once installed as long as water of a river or the like is not dried up. The hydraulic power generating apparatus has an advantage in a point of performing power generation by utilizing water flow which naturally occurs. Here, periodic maintenance is inevitably required to maintain performance thereof. If maintenance is to be performed, it is required to intercept water flow or to perform operation at land after the hydraulic power generating apparatus is lifted from a waterway with a crane and the like. Thus, there is a problem that maintenance requires great care.
The other is a problem of water level fluctuation. There is flow rate fluctuation in a waterway itself corresponding to an irrigation period, a non-irrigation period, a rainy season or a dry season. Since the hydraulic power generating apparatus is installed to a place having water flow such as a river and agricultural waterway, water flow is intercepted to some extent and water level fluctuation occurs at the upstream side and the downstream side. Further, since the power generation amount depends on the water level at the upstream side, there arises difference in power generation amount between a rainy season having a large amount of water and a dry season having a small amount of water. Accordingly, there has been a possible problem that stable power generation cannot be performed.